It is well known to use a stabilizer when extruding a thermoplastic vehicle body molding such as a side molding for a motor vehicle. The stabilizer is molded within the thermoplastic vehicle body molding and is utilized to control shrinkage and thermal expansion of the thermoplastic. A rigid metallic stabilizer, such as aluminum, is commonly utilized due to the fact that its rigidity aids in the extrusion process.
In extruding a thermoplastic vehicle body molding, a two piece stabilizer guide is seated within an extrusion die. The guide comprises two pieces to allow for occasional disassembly and cleaning. The two pieces of the guide abut one another to form a parting line, and a slot is formed that extends the length of the guide and lies in the same horizontal plane as the parting line. The stabilizer is fed through the slot until it exits the guide inside the extrusion die where a thermoplastic material surrounds the stabilizer. The thermoplastic vehicle body molding is then extruded into its final form.
Typically, the metallic stabilizer is a solid sheet of material having a sheet metal thickness and a width narrower than the extruded body molding. When being guided through the slot, the stabilizer may wander into the parting line. The solid sheet of metallic stabilizer does not fray when wandering into the parting line, and therefore, the use of a rigid metallic stabilizer does not generate small frayed pieces that may melt and effect the extrusion process.
The disadvantage of a metallic stabilizer is that the metal adds weight to the thermoplastic vehicle body molding as well as adding cost due to the primer treatment that is required on the metallic stabilizer in order that it may adhere to the thermoplastic. Also, the metallic stabilizer remains visible at the ends of the thermoplastic vehicle body molding which results in the body molding being aesthetically unpleasing. The exposed metallic stabilizer may also produce an edge or corner that may snag or catch on various items during the assembly process.
Stabilizers, such as a non-metallic woven glass mesh, have recently been developed to cure the shortfalls of metallic stabilizers. The non-metallic stabilizers are lightweight, less expensive than metallic stabilizers, inconspicuous and aesthetically pleasing while still being effective in preventing shrinkage and thermal expansion of the thermoplastic vehicle body moldings.
Due to the nature of such non-metallic woven glass mesh stabilizers, processing these stabilizers in the extruding of the thermoplastic vehicle body molding is difficult. As set forth above, the stabilizer guide typically has two halves so that the guide may be disassembled and cleaned on a periodic basis. The horizontal parting line that is created by the abutting halves of the stabilizer presents a problem when utilized with a stabilizer that has a tendency to fray, such as the woven glass mesh. The stabilizer has the propensity to wander into the parting line of the guide, and as a result, the stabilizer becomes frayed and shredded along its edges, sometimes leading to the stabilizer pulling apart. The loose pieces of the stabilizer that shred or fray from the edges of the stabilizer remain in the stabilizer guide and extrusion die and melt from the heat of the extrusion process. When this occurs, the slot becomes obstructed by the melted shreddings of the stabilizer, and the stabilizer is prevented from being fed through the stabilizer guide. This can lead to a shutdown in the extrusion process thus requiring the disassembly and cleaning of the stabilizer guide and the extrusion die. Such shutdowns are costly and inefficient and are not desirable on a production basis.